<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <link rel="stylesheet" href="../bootstrap-3.3.7-dist/css/bootstrap.css">
  <style>
    .item {
      width: 100%;
      height: 200px;
      background: #ff5041;
      margin-bottom: 30px;
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="row">
      <div class="col-md-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-md-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-sm-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-md-6 col-xs-12">
        <div class="item"></div>
      </div>
      <div class="col-md-6 col-xs-12">
        <div class="item"></div>
      </div>
    </div>
  </div>
  
</body>
</html>